1. Field of the Invention
The invention pertains to the field of variable cam timing phasers. More particularly, the invention pertains to cam torque actuated variable cam timing devices with a bi-directional oil pressure bias circuit.
2. Description of Related Art
It has been demonstrated that operating a variable camshaft timing device phaser utilizing the camshaft torque energy to phase the valve timing device is desirable because of the low amount of oil required by a camshaft torque actuated variable camshaft timing device. However, not all engines provide enough camshaft torque energy throughout the entire engine operating range to effectively phase the variable camshaft timing device.